In a medium mixing bowl, whisk together 1 (3.4oz.) box vanilla instant pudding mix, 1½ cups cold whole milk, and 1 cup sour cream until smooth, and the mixture begins to thicken. Set aside.
1 (3.4oz.) box vanilla instant pudding mix, 1½ cups cold whole milk, 1 cup sour cream
Cut the 14 ounce store bought angel food cake into 1-inch cubes and then evenly layer half of the cubes into the bottom of the baking pan.
14 ounce store bought angel food cake
Spread about ⅔ of the 1 (21 oz.) can lemon pie filling on top of the angel food cake, then layer the remaining angel food cake over the top of the lemon filling.
1 (21 oz.) can lemon pie filling
Evenly spread the vanilla pudding mixture over the top of the angel food cake layer.
Then top it with the thawed 8 ounces Cool Whip, spreading it out to fully and evenly cover the pan.
8 ounces Cool Whip
Using a spoon, drop spoonfuls of the remaining lemon pie filling over the cake and swirl it around a bit.
1 (21 oz.) can lemon pie filling
Chill in the refrigerator, uncovered, for 4 to 6 hours or even overnight for a more flavorful and moist cake. Refrigerating it will also help the layers to set. You can tent aluminum foil over the top of the cake if desired.
Right before serving, sprinkle with ¼ cup almond slivers.
¼ cup almond slivers